Support detection of light and dark system colors (#164933)

Part of https://github.com/flutter/flutter/issues/118853

This PR is an enhancement to
https://github.com/flutter/flutter/pull/163335 to provide detection of
system colors for both light and dark mode. This is needed for the
construction of a
[`highContrastTheme`](https://api.flutter.dev/flutter/material/MaterialApp/highContrastTheme.html)
and
[`highContrastDarkTheme`](https://api.flutter.dev/flutter/material/MaterialApp/highContrastDarkTheme.html).
https://dart.googlesource.com/external/github.com/flutter/flutter/+/212f66fbe74eed9c3f2eb955f8fe59bf0a1a4c07
diff --git a/DEPS b/DEPS
index 3834ac6..a95bb19 100644
--- a/DEPS
+++ b/DEPS
@@ -236,7 +236,7 @@
 deps = {
   'flutter/engine/src/flutter/third_party/dart': Var('dart_git') + '/sdk' + '@' + 'e4d9ea38435beece8fd0fb82885188e5d8ea8519',
 
-  'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + '963f23e30e67332ca8b8cd374e4f820e0bc66e4a',
+  'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + '212f66fbe74eed9c3f2eb955f8fe59bf0a1a4c07',
 
   'flutter/engine/src/flutter/third_party/depot_tools':
   Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + '580b4ff3f5cd0dcaa2eacda28cefe0f45320e8f7',
diff --git a/commits.json b/commits.json
index 7f3e294..fb58184 100644
--- a/commits.json
+++ b/commits.json
@@ -1,4 +1,4 @@
 {
-  "flutter":"963f23e30e67332ca8b8cd374e4f820e0bc66e4a",
+  "flutter":"212f66fbe74eed9c3f2eb955f8fe59bf0a1a4c07",
   "flutter/engine/src/flutter/third_party/dart":"e4d9ea38435beece8fd0fb82885188e5d8ea8519"
 }
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